1. Field of the Invention
The present invention relates to an imaging apparatus which allows a color picture image to be obtained by using a single imaging device.
2. Description of Related Art
Hitherto, a single plate type imaging apparatus for imaging a color picture image by using a single imaging device has been used to image video and still picture images. While this imaging apparatus allows a picture image having a number of picture elements equal to a number of photo-receiving domains of the imaging device to be imaged, the resolution of the picture image drops when there is less number of photo-receiving domains in the imaging device. First and second prior art technologies related to imaging apparatuses for improving the resolution of the picture image will be explained below.
The first prior art imaging apparatus is disclosed in Japanese Unexamined Patent Publication JP-A 7-99664 (1995). This imaging apparatus is provided with a color filter which transmits only predetermined three chromatic lights at the light incident side of the photo-receiving domains of the imaging device. In the color filter, only light-transmitting domains which transmit either one of the three colors are arrayed in a diced pattern.
In obtaining an output picture image by this imaging apparatus, the imaging apparatus sequentially shifts the spatial sampling position of the imaging device in the horizontal and vertical directions H and V by a length of a half of a pitch of picture elements so that the spatial sampling position returns to the original position by four fields. The imaging device images picture image light every time when the spatial sampling position is shifted. Then, the picture images obtained by these four times of imaging operations are combined to generate an output picture image composed of picture elements whose number is greater than that of the photo-receiving domains of the imaging device.
The second prior art electronic still camera is disclosed in Japanese Unexamined Patent Publication 6-225317 (1994). FIG. 68 is a block diagram showing the electrical structure of the above-mentioned electronic still camera 1. The electronic still camera 1 has a high definition mode for imaging a high quality picture image. In the high definition mode, a single output picture image signal is generated from four original picture image signals to obtain an output picture image composed of picture elements whose number is greater than a number of photo-receiving domains of an imaging device 4.
When the mode is switched to the high definition mode, picture image light from an object is condensed to a desired state by an optical system 3 and is formed on an image forming plane of the imaging device 4 after passing through a color filter described later. The image forming plane is a two-dimensional plane on which a plurality of photo-receiving domains are arrayed in a matrix form. The color filter is disposed on the light incident side of the image forming plane and transmits only predetermined four chromatic lights. The position for forming the picture image light on the image forming plane is shifted sequentially to first through fourth different image forming positions by a so-called image shifting operation.
FIG. 69 is a diagram showing an array of light-transmitting domains 17 of the color filter 16 of the imaging device 4. The color filter has the same number of light-transmitting domains 17 with the photo-receiving domains of the imaging device 4. The array of the light-transmitting domains 17 is equivalent to the array of the photo-receiving domains and the light-transmitting domains 17 are arrayed in a matrix form with periods PH and PV along the horizontal and vertical directions H and V.
The light-transmitting domains 17 are divided into four kinds of domains each of which transmits only either one of chromatic lights of yellow, cyan, magenta and green. In FIG. 69, each rectangular domain surrounded by a solid line is the light-transmitting domain 17. Symbols xe2x80x9cYexe2x80x9d, xe2x80x9cCyxe2x80x9d, xe2x80x9cMgxe2x80x9d and xe2x80x9cGxe2x80x9d written within the respective rectangular domains denote that color of the chromatic light which can transmit through the light-transmitting domain 17 is yellow, cyan, magenta or green. The array of colors of the light-transmting domains 17 of each chromatic light is a periodic array whose basic array pattern is the array of eight light-transmitting domains 17 in four rows and two columns surrounded by a two-dot chain line 21.
FIG. 70 is a diagram showing the positional relationship of the aforementioned first through fourth image forming positions Qa through Qd. Based on the first position Qa, the second position Qb is the position shifted in the horizontal direction H from the first position Qa by a shift length PH. The third and fourth positions Qc and Qd are the positions shifted from the first position Qa in the same vertical direction V by a shift length PV/2, though in the opposite directions horizontally by a shift length PH/2.
Reference will be made again to FIG. 68. The imaging device 4 receives the formed picture image light by each photo-receiving domain to image the picture image light only for a predetermined exposure time every time when the position for forming the picture image light is shifted to the above-mentioned respective four shift positions and outputs four original picture image signals to a preprocessor circuit 5. This original picture image signal is composed of data of received light which corresponds to a quantity of light received by each photo-receiving domain. The preprocessor circuit 5 amplifies the original picture image signal given from the imaging device 4 and implements a necessary signal processing thereto. The processed signal is converted into a digital signal by an analog/digital converter circuit (abbreviated as an xe2x80x9cA/D circuitxe2x80x9d in the figures) 6 and is then stored in a picture image memory 7.
A signal processing circuit 8 shifts the original picture image represented by the original picture image signals thus obtained in the direction opposite from the shift direction of each of the image forming positions Qa through Qd by the same shift length to superimpose and composite them. Then, based on the received light data of this composite picture image, it generates a luminance signal and a color difference signal of a single output picture image. The generated luminance signal and the color difference signal are recorded in a recording medium 9.
FIG. 71 is a diagram showing an array of picture elements in a part composed of parts corresponding to the aforementioned basic array pattern of each original picture image in the above-mentioned composite picture image. In the figure, rectangular domains indicated by a solid line represent actual picture elements from which components of the luminance signal and the color difference signal of the output picture image may be obtained directly in unit of picture element. Rectangular domains indicated by a broken line represent imaginary picture elements which are obtained by interpolating the luminance signal and the color difference signal from the luminance signal and the color difference signal of the actual picture elements. The actual picture elements marked with xe2x80x9cFaxe2x80x9d correspond directly only to received light data from the photo- receiving domains which receive the light which has passed through the yellow and cyan light-transmitting domains 17. The actual picture elements marked with xe2x80x9cFbxe2x80x9d correspond directly only to received light data from the photo-receiving domains which receive the light which has passed through the green and magenta light-transmitting domains.
In the composite picture image, the actual picture elements which correspond to the yellow and cyan received light data and the actual picture elements which correspond to the green and magenta received light data are arrayed alternately per two rows each. The actual picture elements and the imaginary picture elements adjoin in the horizontal and vertical directions H and V and are arrayed in a diced pattern. The array of picture elements of the output picture image is the same with that of the composite picture image. That is, a number of arrays of the picture elements in the horizontal and vertical directions H and V is doubled and the array period of the picture elements is reduced to a half, respectively.
FIG. 72 is a diagram showing another exemplary positional relationship among the first through fourth image forming positions Qa through Qd in the high resolution mode. Comparing FIG. 72 with FIG. 70, the positional relationship between the first position Qa and the second position Qb is the same. The third and fourth positions Qc and Qd are shifted from the first position Qa in the same vertical direction V by the shift length PV, though in the opposite direction horizontally H by the shift length PH/2.
FIG. 73 is a diagram showing an array of picture elements of the composite picture image in the high resolution mode generated from the four original picture image signals imaged at the shift positions in FIG. 72. Each symbol in the figure means the same with those in FIG. 71. In the composite picture image, the actual picture elements which correspond to the yellow and cyan received light data and the actual picture elements which correspond to the green and magenta received light data are arrayed alternately along the horizontal and vertical directions H and V. Further, rows composed of only the actual picture elements and rows composed of only imaginary picture elements are arrayed alternately. A number of picture elements of the output picture image obtained from this composite picture image is doubled to that of the output picture image in the normal mode with respect to the horizontal direction H and an area per picture element is cut into a half.
Because the array of picture elements is two-dimensional and there are more than three chromatic lights which can transmit the light-transmitting domains of the color filter in the two types of prior art imaging apparatus and the electronic still camera described above, the single output picture image signal is generated based on the four original picture image signals whose image forming positions are different. It is so arranged to be able to generate the luminance signal and the color difference signal separately per each picture element because the output from the photo-receiving domain which receives the chromatic light which has passed through the four kinds of light-transmitting domains corresponds per each picture element of the output picture image when the original picture image signals are composited as described above.
Because the image shifting operation involves the shift in two different directions in obtaining the four kinds of original picture image signals which meet with such condition, the mechanism for shifting the image forming position is complicated. The apparatus having such complicated shift mechanism requires a large number of parts, increasing the production cost. Further, because it requires four picture images of original picture image signals for one output picture image, it requires a memory of four times of capacity, increasing the production cost further, as compared to an apparatus for imaging only in the normal mode.
It is presupposed that an object stands still and the positional relationship between the object and the imaging apparatus does not shift in obtaining the four original picture image signals in the operation for imaging the picture image light in the high resolution mode by these imaging apparatuses. When this presupposition is met, a number of picture elements with respect to the image of the object is increased by registering and superimposing the corresponding images of each of the original picture images by canceling the dislocation caused by the image shifting operation of the four original picture images with respect to the image of the object within the original picture images. At this time, an equivalent imaging time for obtaining the single output picture image is the sum of four times of exposure time of the picture image light and three times of transition time for shifting the image forming position. This equivalent imaging time has the same meaning with a so-called shutter speed of a still camera using a silver-salt film.
When the object moves or the positional relationship is shifted within the equivalent imaging time, the image of the object shifts more than the shift caused by the image shifting operation. In this case, the dislocation of the image of the object cannot be canceled just by the composite process described above. As a result, the image of the object blurs within the composite picture image and the quality of the composite picture image degrades. In particular, the equivalent imaging time is a quite long time which is more than four times of the exposure time in the high resolution mode of the above-mentioned two types of imaging apparatuses. Accordingly, they are susceptible to an influence of the movement of hands and the motion of the object, degrading the quality of the output picture image.
The imaging condition which meets with this presupposition with the above-mentioned imaging apparatuses is a condition in which the object is at rest and the imaging apparatus is used by fixing by a tripod. Accordingly, its use condition has been quite limited as compared to a still camera using a silver-salt film and it has been difficult to use the high resolution mode during the actual imaging operation.
Hence, it is an object of the present invention to provide a single plate type imaging apparatus which allows a high resolution output picture image to be obtained without being influenced by the motion of an object, the movement of hands and the like.
The present invention provides an imaging apparatus comprising;
color separating filter means having a plurality of light-transmitting domains each of which corresponds to one of a plurality of chromatic lights, separately transmits only corresponding chromatic light of a picture image light inputted from an object and which are arrayed in a predetermined array on a two-dimensional plane;
an imaging device for imaging the picture image light and outputting a picture image signal,
the imaging device having photo-receiving domains separately corresponding to the light-transmitting domains of the color separating filter means,
the photo-receiving domains being arrayed on a two-dimensional plane with the same array with the predetermined array of the light-transmitting domains,
each of the photo-receiving domains receiving only chromatic light which has passed through the corresponding light-transmitting domain,
the imaging device outputting the picture image signal composed of picture element data representing a quantity of received light of each photo-receiving domain;
moving means for moving an image forming point of the picture image light inputted to the imaging device to predetermined first and second positions;
exposure permitting means for permitting the imaging device to receive the picture image light for only a predetermined exposure time every time when the image forming point is moved by the moving means;
picture image generating means for generating a composite picture image signal by shifting and superimposing the two outputted picture image signals in a direction opposite from a moving direction of the image forming point by a distance of the image forming points at the time of the imaging operation in response to the output of the imaging device; and
control means for causing the moving means to move the image forming point of the picture image light either to the first or second position when the operation for imaging the picture image light is started, for causing the imaging device to image the picture image light only during the time permitted by the exposure permitting means at that position to give the picture image signal to the picture image generating means, for causing the moving means to move the image forming point to the other position and for causing the imaging device to image the picture image light only during the time permitted by the exposure permitting means at that position to give the picture image signal to the picture image generating means.
According to the invention, the imaging apparatus is a single plate type imaging apparatus for imaging a color picture image by a single imaging device.
The picture image light inputted from the object to the imaging apparatus is inputted to the imaging means after passing through the above-mentioned color separating filter means. The picture image light is separated into a plurality of chromatic lights by passing through the color separating filter means.
A spectrum of each chromatic light exists within a predetermined frequency band and presents an angled waveform centering on one or a plurality of frequencies set in advance. The combination of the plurality of chromatic lights separated by the color separating filter means is selected so as to produce white light when all the chromatic lights are mixed. The combination of such chromatic lights is that of the primary colors of red, blue and green or of the complementary colors of green, yellow, cyan and magenta.
The picture image light which has passed through the color separating filter means is formed on the image forming plane of the imaging device. The luminance of the above-mentioned picture image light changes continuously on spatial axes which are parallel in the one and other directions which are the directions of array of the light-transmitting domains. The imaging device receives each chromatic light component of the picture image light by the plurality of photo-receiving domains arrayed in parallel with the spatial axes. Therefore, an original picture image is a picture image in which the continuous picture image light is smoothed in unit of the photo-receiving domain. It is equivalent to that the picture image light whose luminance changes continuously is sampled in unit of the photo-receiving domain. It is preferable to form the color separating filter means in a body with the imaging device described above.
In connection with the imaging device, the exposure permitting means is provided. The exposure permitting means causes each photo-receiving domain of the imaging device to receive the picture image light only for a predetermined exposure time during one time of operation for imaging the picture image light. The picture element data of the above-mentioned original picture image signal indicates a quantity of chromatic light received by each light receiving element during the exposure time. The imaging device outputs the picture element data from each photo-receiving domain by a certain method after the elapse of the exposure time. Thereby, the picture image light is imaged. The original picture image is a picture image obtained by imaginarily and visually displaying the original picture image signal.
The moving means is provided on the light incident side of the image forming plane of the imaging device for example. The operation for moving the image forming point which is the point where the inputted picture image light is formed on the image forming position to the predetermined two locations as described above will be referred to as a two-position image shifting operation. Every time when the image forming point is moved by the moving means, the imaging device capture the picture image light by the procedure described above and outputs the original picture image signal. Thereby, the imaging device outputs the two original picture image signals whose image forming points are different.
The picture image generating means generates the composite picture image signal representing the composite picture image by the above-mentioned method from these two original picture image signals. The picture image generating means also generates a luminance signal and two kinds of color difference signals from picture element data with respect to each picture element of the composite picture image and generates an output picture image signal composed of those signals. It may also perform an interpolation process of the output picture image signal based on the composite picture image.
As described above, the inventive imaging apparatus generates the single composite picture image signal from the two original picture image signals obtained by performing the two-position image shifting operation. An equivalent imaging time may be considered as a criterion of the degree of influence given to the quality of the composite picture image by the movement of hands and the motion of the object during the imaging operation of the imaging apparatus which performs the image shifting operation. The equivalent imaging time is an operation time in imaging the picture image light to obtain the single output picture image signal and has the same meaning with a so-called shutter speed of a still camera using a silver salt film. The greater the equivalent imaging time, the more susceptible the composite picture image and the output picture image based on that is to the movement of hands and the motion of the object during the imaging operation. Accordingly, the blur of the picture image caused by the movement of hands and the motion of the object becomes larger in almost proportion to the increase of the equivalent imaging time for example.
The equivalent imaging time of the inventive imaging apparatus is the sum of two times of the exposure times and one time of the image forming point transition time. As described before, the equivalent imaging time of the prior art imaging apparatus is the sum of four times of exposure times and three times of transition time. When the exposure time and the transition time of the prior art and the present invention are equal, the equivalent imaging time of the inventive imaging apparatus is shorter by the two times of exposure times and transition times as compared to the equivalent imaging time of the prior art imaging apparatus. Because the transition time is longer than the exposure time in general, the equivalent imaging time of the present invention is less than the half of the equivalent imaging time of the prior art. Accordingly, the inventive imaging apparatus receives less influence of the movement of hands and the motion of the object and the quality of the composite picture image degrades less as compared to the prior art imaging apparatus. Therefore, the imaging condition which allows the resolution to be improved is eased by the imaging apparatus using the image shifting operation.
Because there have been two or more directions in which the image forming point is moved from the reference position to the other positions in the four-position image shifting operation of the prior art, the moving means has had a structure having two or more displacement axes of the image forming point. The more the number of the displacement axes, the more complicated the structure of the moving means becomes in general. The inventive imaging apparatus performs the two-position image shifting operation, so that the image forming point is moved only in the one direction from a first position to a second position or in the one direction opposite from that. Thereby, the structure of the moving means is simplified because it just needs to be provided with a single displacement axis. Thereby, the control of the moving means is also simplified and the production cost of the moving means is reduced.
The imaging apparatus using the image shifting means obtains the plurality of original picture image signals by using the imaging device in a time-division manner. Because the imaging device itself has often no structure for storing the plurality of original picture image signals, the picture image composing means has a memory for storing the original picture image signals which cannot be stored by the imaging device from the time of imaging the picture image light at the first time to the last imaging operation. In the prior art imaging apparatus performing the four-position image shifting operation, the memory has had to store at least three previous original picture image signals before the last imaging operation. Because the inventive imaging apparatus performs the two-position image shifting operation, it needs to store just a single original picture image signal at the last imaging operation. Accordingly, the capacity of the memory to be prepared may be reduced. Thereby, the production cost with regard to the memory may be reduced.
The invention is characterized in that:
the composite picture image signal is composed of plurality of picture element data,
the imaging apparatus further comprises display means having a visual display area for visually displaying the composite picture image represented by the composite picture image signal,
the visual display area being formed by a plurality of display picture elements for visually displaying each picture element data of the composite picture image signal arrayed in a matrix form on a two-dimensional plane in parallel with the predetermined main scan and sub-scan directions which cross each other at right angles,
the display picture elements along the main scan direction having an arrayed number greater than an arrayed number of the display picture elements along the sub-scan direction; and
the first and second positions are separated in the direction in which Moire of a spatial frequency in the main scan direction of the composite picture image may be canceled.
According to the invention, the imaging apparatus is provided with the above-mentioned display means. This display means may be realized by a cathode ray tube for example. For instance, a cathode ray tube for visually displaying video signals of the NTSC system television scans the phosphor screen by an electron beam of analog signals sequentially along the main and sub-scan directions. A number of picture elements in the main scan direction is almost infinite in the cathode ray tube. Because a number of picture elements in the sub-scan direction is equivalent to a number of so-called scan lines, it is finite and is 512 in the NTSC system.
The number of picture elements composing the composite picture image is increased in improving the resolution of the composite picture image by the above-mentioned imaging apparatus. At this time, unless the display means for visually displaying the composite picture image signal is constructed so as to be able to display the increased picture elements separately, the improved picture image cannot be displayed even if its resolution is improved in the signal stage. While a finite number of photo-receiving domains are arrayed in parallel with the main and sub-scan directions, the number of picture elements in the sub-scan direction often coincides with the number of scan lines in that direction in the display means in a typical imaging device. Therefore, it is preferable to improve the resolution in the main scan direction in which the display picture elements can be increased at least in the visual display area of the display means in improving the resolution of the picture image by performing the two-position image shifting operation by the imaging apparatus using this imaging device.
As a method for improving the resolution of the picture image in the main scan direction, there may be cited a method of extinguishing Moire on the spatial frequency axis corresponding to the spatial axis parallel with the main scan direction among Moire appearing within a normal band of a signal on the spatial frequency plane of the picture image signal for example. The reason why the resolution is improved by this method will be shown below.
The resolution of a picture image in the direction parallel to a certain spatial axis improves in proportion to a width of a normal band of a picture image signal on a spatial frequency axis corresponding to that spatial axis. When the picture image signal causes color Moire, an optical low-pass filter is inserted to the optical system of the imaging apparatus for example to damp the spatial frequency component which causes the color Moire from the picture image light to eliminate the color Moire. Although the color Moire fringe is eliminated from the picture image by carrying out this processing, the width of the normal band is limited to be less than the spatial frequency which caused the color Moire. As a result, the substantial width of the normal band of the picture image signal is narrowed, reducing the resolution of the picture image.
When the Moire on the spatial frequency axis in the main scan direction is extinguished, the width of the normal band of the picture image signal needs not be limited for the Moire, so that the original width of the normal band may be kept. Accordingly, it allows the same effect with expanding the width of the normal band to be obtained and the resolution of the picture image to be improved. The aforementioned first and second positions are selected so as to have the positional relationship so that the effect of extinguishing the Moire as described above can be obtained in generating the composite picture image signal.
The color Moire on the spatial frequency axis in the main scan direction appears as color Moire fringes to a fringe pattern parallel to the sub-scan direction on the picture image. This color Moire is caused when a desired signal component of the luminance signal interferes with the return component of the color difference signal because there is a difference between sampling frequencies of the luminance signal and the color difference signal of the picture image signal on the spatial frequency axis. The sampling frequency of the luminance signal corresponds an array period of all the picture elements composing the picture image represented by the picture image signal. The sampling frequency of the color difference signal corresponds to an array period of an array composed only of picture elements corresponding to photo-receiving domains receiving a single chromatic light among all the picture elements of the picture image. The color Moire is extinguished when these two sampling frequencies are made to coincide.
In the original picture image signal obtained by the single plate type imaging apparatus, an array corresponding to the color difference signal is equivalent to an array of only light-transmitting domains corresponding to a certain chromatic light in the color separating filter means. Further, in the composite picture image signal of the apparatus, the array corresponding to the color difference signal is equivalent to an array of only light-transmitting domains corresponding to a certain chromatic light in the imaginary color separating filter means. This imaginary color separating filter is assumed to be a filter in which two color separating filters of the imaging apparatus are registered by shifting in the direction of separation and by the distance of the first and second positions. Accordingly, the closer the above-mentioned array in the imaginary color separating filter is to the array of all the light-transmitting domains of the imaginary color separating filter means, the closer the sampling frequencies of the luminance signal and the color difference signal becomes, thus hardly causing the color Moire. Accordingly, it is preferable to set the first and second positions so that such imaginary color separating filter means can be assumed in imaging the composite picture image.
The invention is also characterized in that:
the light-transmitting domains of the color separating filter means are divided into first through fourth light-transmitting domains which transmit predetermined first through fourth chromatic lights;
the predetermined array of the light-transmitting domains is an array in a matrix form in which the light-transmitting domains are arrayed respectively in parallel with one and other directions which cross each other at right angles in the one direction with a predetermined first period and in the other direction with a predetermined second period,
a first group in which the first and fourth light-transmitting domains are arrayed alternately and linearly in the one direction and a second group in which the second and third light-transmitting domains are arrayed alternately and linearly in the one direction are disposed alternately in the other direction,
the first light-transmitting domain and the fourth light-transmitting domain adjoin the second light-transmitting domain in the other direction and a direction opposite thereto, respectively, and
the second light-transmitting domains adjoin the fourth light-transmitting domain in the other direction and the direction opposite thereto;
the imaging device mixes the picture element data from each photo-receiving domain per two each photo-receiving domain adjoining in the other direction or in the direction opposite thereto to output in a batch;
the first position is a predetermined reference position; and
the second position is a position shifted in parallel to the one direction by the length of the first period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the two-position image shifting operation in parallel to the one direction in the imaging apparatus having the aforementioned color separating filter means which transmit the four complementary colors of chromatic lights for example and using a so-called two-picture element mixed reading type imaging device.
As compared to the original picture image signal, although the shape of the normal band of the composite picture image signal does not change, the array period of the array of picture elements in the one direction corresponding to the above-mentioned chromatic lights is reduced to a half. Thereby, Moire appearing on the spatial frequency axis corresponding to the one direction in the original picture image signal all disappear in the composite picture image signal. Therefore, it becomes unnecessary to limit the spatial frequency component of the picture image light in the one direction by the optical low-pass filter. Accordingly, the substantial width of the normal band of the picture image signal is expanded with respect to the one direction.
When the one direction is the main scan direction of the display means described above, the Moire of the composite picture image displayed on the display means is reduced and the picture image quality is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The invention is also characterized in that:
the light-transmitting domains of the color separating filter means are divided into first through fourth light-transmitting domains which transmit predetermined first through fourth chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in a matrix form, in which the light-transmitting domains are arrayed respectively in parallel with one and other predetermined directions which cross each other at right angles in the one direction with a predetermined first period and in the other direction with a predetermined second period,
the fourth light-transmitting domains adjoin the first light-transmitting domain in the one direction and in a direction opposite thereto, the second light-transmitting domain adjoins thereto in the other direction and the third light-transmitting domain also adjoin thereto in a direction opposite to the other direction, and
the second light-transmitting domain adjoins the fourth light-transmitting domain in the direction opposite from the other direction;
the imaging device outputs the picture element data from each of the photo-receiving domains separately;
the first position is the predetermined reference position; and
the second position is a position shifted in parallel to the one direction by the length of the first period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the parallel two-position image shifting operation in parallel to the one direction in the imaging apparatus having the aforementioned color separating filter means which transmit the four complementary colors of chromatic lights for example and using a so-called whole picture element reading type imaging device.
As compared to the original picture image signal, although the shape of the normal band of the composite picture image signal does not change, the array period of the array of picture elements in the one direction corresponding to the above-mentioned chromatic lights is reduce to a half. Thereby, Moire appearing on the spatial frequency axis corresponding to the one direction in the original picture image signal all disappear in the composite picture image signal. Therefore, it becomes unnecessary to limit the spatial frequency component of the picture image light by the optical low-pass filter and the substantial width of the normal band of the picture image signal is expanded.
The return frequency of the return component of the color difference signal which causes Moire remains only at the intersection of the spatial frequency axis in the other direction with the boundary of the normal band in the composite picture image signal. The the desired signal component of the luminance signal and color difference signal necessary in displaying the picture image changes angularly centering on the origin of the spatial frequency axis, so that the amplitude near the boundary of the normal band is small. Even if the signal amplitude near the boundary is reduced, there is less influence to the desired signal component. Further, even if the optical low-pass filter is inserted to the optical system to limit the width of the normal band to eliminate the Moire, the width barely changes before and after the limitation. Accordingly, the influence of Moire with respect to the other direction is small.
When either one of the one direction or the other direction is assumed to be the main scan direction of the display means described above, the Moire of the composite picture image displayed on the display means is reduced and the picture image quality is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The present invention is also characterized in that:
the light-transmitting domains of the color separating filter means are divided into first through third light-transmitting domains which transmit predetermined first through third chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in a matrix form in which the light-transmitting domains are arrayed respectively in parallel with one and other predetermined directions which cross each other at right angles in the one direction with a predetermined first period and in the other direction with a predetermined second period,
the second light-transmitting domain adjoins the first light-transmitting domain in the one direction, the third light-transmitting domain adjoins thereto in a direction opposite to the one direction, and the other first light-transmitting domains also adjoin thereto in the other direction and in a direction opposite thereto,
the third light-transmitting domain adjoins the second light-transmitting domain in the one direction and the other second light-transmitting domains also adjoin thereto in the other direction and in the direction opposite thereto, and
the other third light-transmitting domains adjoin the third light-transmitting domain in the other direction and in the direction opposite thereto;
the imaging device mixes the picture element data from each photo-receiving domain per two each photo-receiving domain adjoining in the other direction or in the direction opposite thereto to output in a batch;
the first position is a predetermined reference position; and
The second position is a position shifted in parallel to the one direction by a length of one and one-half times the length of the first period from the first position and in parallel to the other direction by a length of a half of the length of the second period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the diagonal two-position image shifting operation to the first and second positions in the above-mentioned positional relationship in the imaging apparatus having the aforementioned color separating filter means which transmit the three primary colors of chromatic lights for example and using a so-called two-picture element mixed reading type imaging device.
As compared to the original picture image signal, the width of the normal band on the spatial frequency axes in one and other directions of the composite picture image signal is doubled. Further, the array period of the array of picture elements corresponding to the color difference signal is doubled with respect to the one direction, so that the distance from the origin of Moire appearing on the spatial frequency axis in the one direction in the original picture image signal is doubled. Thereby, the substantial width of the normal band of the composite picture image signal after inserting the optical low-pass filter is doubled with respect to the both of one and other directions as compared to the substantial width of the original picture image signal.
When the one direction is assumed to be the main scan direction of the display means described above, the resolution is improved twice after removing the Moire and the quality of the composite picture image is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The invention is characterized in that:
the light-transmitting domains of the color separating filter means are divided into first through third light-transmitting domains which transmit predetermined first through third chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in a matrix form in which the light-transmitting domains are arrayed respectively in parallel with one and other predetermined directions which cross each other at right angles in the one direction with a predetermined first period and in the other direction with a predetermined second period,
the second light-transmitting domain adjoins the first light-transmitting domain in the one direction, the third light-transmitting domain adjoins thereto in a direction opposite from the one direction, and the other first light-transmitting domains also adjoin thereto in the other direction and in a direction opposite thereto,
the third light-transmitting domain adjoins the second light-transmitting domain in the one direction and the other second light-transmitting domains also adjoin thereto in the other direction and in the direction opposite thereto, and
the other third light-transmitting domains adjoin the third light-transmitting domain in the other direction and in the direction opposite thereto;
the imaging device outputs the picture element data from each photo-receiving domain separately;
the first position is a predetermined reference position; and
the second position is a position shifted in parallel to the one direction by a length of two-thirds of the length of the first period from the first position and in parallel to the other direction by a length of a half of the length of the second period from the first position Qa4.
According to the invention, it is preferable to obtain the composite picture image signal by performing the diagonal two-position image shifting operation to the first and second positions in the above-mentioned positional relationship in the imaging apparatus having the aforementioned color separating filter means which transmit the three primary colors of chromatic lights for example and using the so-called whole picture element reading type imaging device.
As compared to the original picture image signal, the width of the normal band on the spatial frequency axes in one and other directions of the composite picture image signal is doubled. Further, the array period of the array of picture elements corresponding to the color difference signal is doubled with respect to the one direction, so that the position of Moire appearing on the spatial frequency axis in the one direction in the original picture image signal becomes distant from the origin twice. Thereby, the substantial width of the normal band of the composite picture image signal after inserting the optical low-pass filter is doubled with respect to the both of one and other directions as compared to the substantial width of the original picture image signal.
Accordingly, when either one of one or the other direction is assumed to be the main scan direction of the display means described above, the resolution is improved twice after removing the Moire and the quality of the composite picture image is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The invention is also characterized in that:
the plurality of light-transmitting domains of the color separating filter means are divided into first through third light-transmitting domains which transmit predetermined first through third chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in which groups of light-transmitting domains arrayed linearly with a first period in parallel to a predetermined one direction are arrayed in an other direction which crosses at right angles with the one direction with a second period and the position of each light-transmitting domain in the two groups adjoining in the other direction is shifted in the one direction by a length of the half of the first period,
the second light-transmitting domain adjoins the first light-transmitting domain in the one direction and the third light-transmitting domain adjoins thereto in a direction opposite from the one direction, and
the third light-transmitting domain adjoins the second light-transmitting domain in the one direction and the first light-transmitting domain adjoins thereto in a third direction shifted in the one direction by a half of the first period and in the other direction by a length of the second period;
the imaging device outputs the picture element data from each photo-receiving domain separately;
the first position is a predetermined reference position; and
the second position is a position shifted in parallel to the other direction by a length of the second period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the vertical two-position image shifting operation vertical to the one direction in the imaging apparatus having the aforementioned color separating filter means which transmit the three primary colors of chromatic lights for example and using the so-called whole picture element reading type imaging device.
As compared to the original picture image signal, the width of the normal band on the spatial frequency axis in the diagonal direction of the composite picture image signal is doubled. The diagonal direction is defined by a vector which reaches to a point shifted from the origin of the spatial frequency axis in parallel to the one direction by the length of the first period and in parallel to the other direction by a length of a half of the second period. Thereby, the substantial width of the normal band of the composite picture image signal after inserting the optical low-pass filter is expanded with respect to the diagonal direction.
Accordingly, when either the one or the other direction is assumed to be the main scan direction of the display means described above, the resolution is improved after removing the Moire and the quality of the composite picture image is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The invention is also characterized in that:
the plurality of light-transmitting domains of the color separating filter means are divided into first through third light-transmitting domains which correspond to predetermined first through third chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in a matrix form in which the light- transmitting domains are arrayed respectively in parallel with one and other predetermined directions which cross each other at right angles in the one direction with a predetermined first period and in the other direction with a predetermined second period;
a first linear group in which the first and second light-transmitting domains are arrayed alternately in parallel to the one direction and a second linear group in which the first and third light-transmitting domains are arrayed alternately in parallel to the one direction are disposed alternately in the other direction, and
the third light-transmitting domains adjoin the first light-transmitting domain in the first group in the other direction and a direction opposite thereto;
the imaging device outputs the picture element data from each photo-receiving domain separately;
the first position is a predetermined reference position; and
the second position is a position shifted in parallel to the one direction by a length of the first period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the two-position image shifting operation parallel to the one direction in the imaging apparatus having the aforementioned color separating filter means which transmit the three primary colors of chromatic lights for example and using the so-called whole picture element reading type imaging device.
As compared to the original picture image signal, although the shape of the normal band does not change, the array period of the array of picture elements corresponding to the above-mentioned chromatic lights in the one direction is reduced to a half. Thereby, the Moire appearing on the spatial frequency axis corresponding to the one direction in the original picture image signal all disappear in the composite picture image signal. Accordingly, it becomes unnecessary to limit the frequency component of the picture image light by the optical low-pass filter and the substantial width of the normal band is expanded.
The return frequency of the return component of the color difference signal which causes Moire remains only at the intersection of the spatial frequency axis in the other direction with the boundary of the normal band in the composite picture image signal. When the width of the normal band is limited so as to remove the Moire, the width barely changes before and after the limitation, so that the influence of Moire with respect to the other direction is considered to be small.
When either one of one or the other direction is assumed to be the main scan direction of the display means described above, the Moire of the composite picture image displayed on the display means is reduced and the quality of the composite picture image is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
The invention is also characterized in that:
the plurality of light-transmitting domains of the color separating filter means are divided into first through third light-transmitting domains which correspond to predetermined first through third chromatic lights, respectively;
the predetermined array of the light-transmitting domains is an array in which a first group in which the first and second light-transmitting domains are arrayed linearly in parallel to one predetermined direction with a first period and a second group in which the first and third light-transmitting domains are arrayed linearly in parallel to the one direction with the first period are arrayed alternately with a predetermined second period in an other direction which crosses at right angles with the one direction, and
the third light-transmitting domain adjoins the first light-transmitting domain in the first group in a direction shifted in parallel to the one direction by a length of a half of the first period and in parallel to the other direction by a length of the second period;
the imaging device outputs the picture element data from each photo-receiving domain separately;
the first position is a predetermined reference position; and
the second position is a position shifted in parallel to the one direction by a length of the first period from the first position.
According to the invention, it is preferable to obtain the composite picture image signal by performing the parallel two-position image shifting operation parallel to the one direction in the imaging apparatus having the aforementioned color separating filter means which transmit the three primary colors of chromatic lights for example and using the so-called whole picture element reading type imaging device.
As compared to the original picture image signal, although the shape of the normal band does not change, the array period of the array of picture elements corresponding to the above-mentioned chromatic lights in the one direction is reduced to a half. Thereby, the distance of the position of the Moire appearing on the spatial frequency axis corresponding to the one direction in the original picture image signal from the origin is doubled and the position of Moire moves on the intersection of the boundary of the normal band with the spatial frequency axis. Accordingly, the substantial width of the normal band after inserting the optical low-pass filter expands.
The return frequency of the return component of the color difference signal which causes Moire remains only at the intersection of the spatial frequency axis in the other direction with the boundary of the normal band in the composite picture image signal. When the width of the normal band is limited so as to remove the Moire, the width barely changes before and after the limitation, so that the influence of Moire with respect to the other direction is considered to be small.
When either one of one or the other direction is assumed to be the main scan direction of the display means described above, the Moire of the composite picture image displayed on the display means is reduced and the quality of the composite picture image is improved. Thereby, the picture image quality may be improved further not only by preventing the degradation of the picture image quality caused by the movement of hands and the motion of the object by the two-position image shifting operation but also by eliminating the drop of the resolution caused by the Moire.
Further, the invention is characterized in that:
the exposure permitting means comprises first permitting means for permitting/inhibiting electric charge to be accumulated in the photo-receiving domains of the imaging device, and second permitting means for transmitting/shutting off the picture image light to be inputted to the imaging device; and
in imaging the image light at the either one position among the first and second positions, the control means causes the second permitting means to transmit the picture image light and causes the first permitting means to permit to accumulate electric charge only during the exposure time, and
in imaging the image light at the other position among the first and second positions, the control means causes the first permitting means to permit to accumulate electric charge in the photo-receiving domains and causes the second permitting means to transmit the picture image light only during the exposure time.
According to the invention, the above-mentioned imaging device may be realized by a so-called two-dimensional CCD image sensor. When the chromatic light enters the photo-receiving domains within a photoelectric conversion time set in advance for the imaging device, the sensor transforms the chromatic light photoelectrically and accumulates the obtained electric charge. The charge accumulated within the photoelectric conversion time is output out of the imaging device after the elapse of the time as the picture element data via transfer charge coupled devices (CCD). The time from the end of the photoelectric conversion time till when the picture element data is output from all the photo-receiving domains to the outside will be referred to as a transfer time. The transfer time is longer than the sum of the exposure time and the transition time described before in general.
Such imaging device includes an electronic shutter utilizing an overflow drain as the first permitting means of the exposure control means. This electronic shutter operates by opening the overflow drain and inhibiting the photo-receiving element from holding the charge. Using such first permitting means in imaging the picture image light in the first time at either one position allows the exposure time during the imaging operation of the first time to be shortened to be less than the photoelectric conversion time intrinsic to the imaging device.
The electronic shutter cannot be used when electric charge of the other picture element data is included in the transfer charge coupled devices. Therefore, when the exposure time is controlled only by the electronic shutter, the time from the end of the exposure of the first time to the beginning of the exposure of the second time is determined by the transfer time. Accordingly, the equivalent imaging time at this time is the sum of the two times of exposure time and the transfer time.
The imaging apparatus has mechanical shutter means for example as second permitting means of the exposure control means. In imaging the picture image light in the second time at either of the other position, the control means control the exposure time by directly transmitting/shutting off the picture image light itself which is to enter the imaging device by the second permitting means, instead of the electronic shutter. Controlling the exposure time as described above allows the exposure of the second time to be implemented in the photo-receiving domains in parallel even during the time when the transfer charge coupled devices transfer the original picture image signal of the first time.
Thus, the imaging apparatus controls the exposure time in imaging the picture image light by using the electronic shutter of the two-dimensional CCD image sensor together with the mechanical shutter means. Thereby, the imaging operation of the image light in the second time may be implemented even if the transfer charge coupled devices of the image sensor are in the operation state. Because the equivalent imaging time is the sum of the two times of exposure time and the transition time at this time, the equivalent imaging time may be shortened as compared to the case of controlling the exposure time only by the electronic shutter. Therefore, it further allows to prevent the degradation of quality of the composite picture image caused by the movement of hands and the motion of the object.
The invention is characterized in that:
the imaging apparatus further comprises an optical system for condensing the picture image light to form on the two-dimensional plane of the imaging device; and
the moving means comprises:
a plate-like refracting plate having a light-transmitting quality,
a pair of bimorph type piezoelectric elements which are disposed on the both sides of the refracting plate so that the surface thereof is almost parallel to the surface of the refracting plate, in which one free end in a longitudinal direction of the elements is bonded with one end of the refracting plate to support the refracting plate so that the other end of the refracting plate extends toward the fixed end on the other side of the elements and which inclines the refracting plate centering on an imaginary center of rotation which passes within the refracting plate,
detecting means for detecting an inclination formed between an optical axis of the optical system and a normal line of the refracting plate,
comparator means for comparing output of the detecting means with a predetermined target value to output the error thereof, and
driving means for driving the pair of bimorph type piezoelectric elements in response to output of the comparator means so that the inclination of the refracting plate coincides with the predetermined target value.
According to the invention, the moving means has the above-mentioned structure. This moving means has less components and facilitates the miniaturization of each component including the inclined plate. Accordingly, it allows the structure of the whole moving means to be simplified and miniaturized. It allows to use as a portable imaging apparatus. Further, because the moving means is controlled by the so-called feedback control, the image forming point may be displaced reliably by moving the optical axis in parallel by a desired distance.
The invention is characterized in that:
the imaging apparatus further comprises an optical system for condensing the picture image light to form on the two-dimensional plane of the imaging device; and
the moving means comprises:
a pair of transparent plates having imaginary centers of rotation which cross each other at right angles, inclining means for inclining the transparent plates centering on each imaginary center of rotation,
a refracting substance layer which is interposed between the transparent plates, which can be deformed and which has a refractive index greater than that of air,
detecting means for detecting an inclination formed between an optical axis of the optical system and a normal line of each transparent plate,
comparator means for comparing output of the detecting means with a predetermined target angle to output the error thereof, and
driving means for driving the inclining means in response to output of the comparator means so that the inclination coincides with the predetermined target angle.
According to the invention, the moving means may be realized by a so-called variable vertical angle prism. Because the variable vertical angle prism is used in an optical blur compensator of a video camera, the prism of that apparatus may be used also as the moving means for shifting the picture image. Accordingly, a number of parts of the apparatus may be reduced by assembling the blur compensator within the imaging apparatus.
The invention is characterized in that:
the imaging apparatus further comprises:
move determining means for permitting/inhibiting the move of the image forming point in the moving means; and
a variable spatial filter for damping the spatial frequency component of the picture image light to be inputted to the imaging device, i.e. damping the spatial frequency component by a first decrement when the move of the image forming point is inhibited and damping it by a second decrement when it is permitted.
According to the invention, the imaging apparatus has two modes and outputs picture image signals having two kinds of resolution. It outputs the original picture image signals as they are in one mode and generates and outputs a composite picture image signal from the original picture image signals in the other mode. The number and positions of Moires are different in these two picture image signals as described before. Accordingly, when the decrement of the optical low-pass filter interposed in the optical system is adjusted to the original picture image signal, the normal band of the composite picture image signal whose resolution has been improved is limited excessively, degrading the resolution of the composite picture image after the limitation more than that of the composite picture image before the limitation. When the decrement is adjusted to the composite picture image signal on the other hand, the normal band of the original picture image signal is limited insufficiently, causing Moire in the original picture image.
In the inventive imaging apparatus, the quality of the both original picture image and composite picture image may be fully kept by switching the two modes by permitting/inhibiting the move of the image forming point as described above and by changing the decrement of the spatial filter which is the optical low-pass filter.